ALERT For Accumulating Snow At Upper Elevations Into Sunday Morning ( Mainly Above 3000 Feet )
A large temperature plunge will occur overnight into Sunday morning with rain showers changing to snow showers and flurries. A Great Lake moisture linkage will combine with upsloping NW winds to cause an enhanced period of snow showers.
Accumulations of up to 1″, or locally more at highest elevations in the High Knob Massif, will contrast with little to no accumulation at elevations below 2500 to 3000 feet.
Low clouds are expected to break during mid to late Sunday afternoon, with unseasonably cold conditions continuing into April 1.
European Ensemble Mean 500 MB Height Anomalies Forecast_Days 3-7
A milder zonal flow is now expected to develop across the USA with a warming trend during the first week of April, following a chilly start to the new month.
February 2019_850 MB Temperature Anomalies
For the second consecutive year, the month of March will end having been colder than February ( above ) versus long-term averages.
ALERT For Dropping Cloud Bases And A Period Of Dense Fog On Northerly Upslope Flow Along And North Of The High Knob Massif-Tennessee Valley Divide Monday Evening Into Early Tuesday
Developing rain, with a chance of thunder, will give way to an influx of colder air by Monday evening into early hours of Tuesday with dropping cloud bases.
Northerly upslope flow will lower cloud bases to generate dense fog at elevations around and above the elevation of the Town of Wise. Caution is advised for reduced visibility from late Monday into early hours of Tuesday.
Very Dense Fog_University Of Virginia’s College At Wise
Please use extreme caution for greatly reduced visibility through this morning (Tuesday).
Freezing fog, with riming, is expected at elevations above 3000-3300 feet.
European Model 850 MB Temp-Wind Flow Forecast_Friday_March 29, 2019
A changeable spring weather pattern is featured for the final days of March into early April, with a huge temperature fluctuation expected from unseasonable warmth to unseasonably cold air.
European Model 850 MB Temp-Wind Flow Forecast_Sunday_March 31, 2019
The late March-early April setting will bear close watching with high latitude blocking. This will generate the potential for a large storm system.
European Model 500 MB Height Anomalies_Sunday_March 31, 2019
Wind driven snow will impact high elevations into tonight, with caution advised for travelers crossing the High Knob Massif on Route 619 and connecting roads above 3300 feet.
Eagle Knob of High Knob Massif At 2:34 PM_March 21, 2019
Gusty NW winds and falling snow will combine with orographic clouds to cause greatly reduced visibility. Accumulations of 1-3″ are expected to be widespread on ground surfaces, with much less on roads during the day. Greatest sticking on roads is expected to occur after sunset.
Little to no accumulation is expected at elevations below 2700-3000 feet, with sticking at these lower elevations expected tonight in snow showers.
ALERT For Strong S-SW Winds Through Today And The Potential Of Strong To Severe Thunderstorms By Late Today And Tonight (March 14)
A powerful low pressure system lifting into the upper Great Lake will continue to generate strong and gusty S-SW winds across the mountains.
The Storm Prediction Center Has A Marginal To Slight Risk Predicted For Counties Along The VA-KY Border
Strong-severe thunderstorms will also be developing by Thursday afternoon west of the Appalachians and will need to be monitored by late today into tonight as they approach from the west and southwest.
Updated Storm Prediction Center Risk
Due to significant wind shear, thunderstorms which can become severe will have a tornado potential.
Updated Storm Prediction Center Tornado Risk
While the main risk will be across central Tennessee and Kentucky, these thunderstorms will need to be closely monitored as they approach the VA-KY stateline by Thursday evening.
Forecast Sounding Above Wise By 2:00 AM Friday_March 15, 2019
Conditions for strong-severe thunderstorms become most favorable by tonight into the early overnight of early Friday ( 55% probability of a supercell using the SPC composite forecast sounding above for Wise ).
HRRR Model Forecast Doppler Radar At 11:00 PM Thursday_March 14, 2019
Storms are moving so fast that conditions will begin to rapidly change after 8:00 PM this evening. The current HRRR Model is predicting a broken line of supercells, or strong-severe thunderstorms, to be just west of the mountains by 11:00 PM.
High shear but limited instability will be competing to spin-up supercell storms, with numerous other parameters favorable for strong to severe storms.
The severe thunderstorm potential rapidly diminishes between 2 AM and 8 AM Friday.
Stay tuned to NOAA Weather Radio and your favorite media sources for updates and any possible watches and warnings which may be needed.
ALERT For Strong SSE-SSW Winds Developing Saturday Afternoon Into Saturday Night
A strong pressure gradient will develop generally strong winds across the mountain region during Saturday afternoon into Saturday night, with developing rain showers and the chance for thunderstorms.
Strongest general winds are expected in upper elevations at 30-50+ mph speeds, with locally higher gusts, and in mountain wave breaking zones where local gusts to hurricane force will be possible.
Previous Alerts
High Knob Massif Webcam_University Of Virginia’s College At Wise
Wintry conditions dominated the first 8 days of March, with 3-4″+ of snowfall observed from the elevation of the High Chaparral and Robinson Knob communities upward in elevation within the High Knob Massif (1.4″ Clintwood ). Still much more rain than snow, a trend that will continue.
ALERT For Hazardous Conditions Friday AM
A period of moderate to heavy snow will impact the mountain area Friday morning. Accumulations of 1″ to 3″ are expected at mid-upper elevations, with up to 1″ at lower elevations, prior to changing to mix-rain, within locations along and north of the High Knob Massif-Tennessee Valley Divide.
Most of the past four days have been below freezing (and remain below freezing at highest elevations), such that ground surfaces are cold.
Snow will be developing during the predawn-early morning before surfaces have a chance to warm. Caution is advised.
Weather Headlines ( March 4-11 )
High Knob Massif Webcam_University Of Virginia’s College At Wise
A gorgeous array of rime covers a huge area along the common borders of Wise-Scott and Lee-Harlan counties, with a little even decorating the Wise-Sandy Ridge plateaus.
A cold pattern is currently gripping the mountain landscape, with Monday featuring daytime temps in the 10s across upper elevations and the 20s in places at lower-middle elevations along and north of the High Knob Massif and Tennessee Valley Divide.
European 51-Member Ensemble Mean 500 MB Height Anomaly Forecast_Days 5-9
Looking ahead the pattern will be reverting back to what dominated most of February 2019.
This means more concerns for high water events are upcoming as a series of waves move across the Pacific Ocean and the continental USA.
Composite Climatology For 9 Different Flood Events_Mean 500 MB Height Anomalies
While a composite of 9 historic flood events reveals a somewhat sharper wave amplitude, and slight eastward displacement, it is otherwise strikingly similar to the February 2019 pattern.
The similarity of the February 2019 pattern and a composite of 9 past flood events is rather striking.
Composite Climatology For 9 Different Flood Events_Mean 850 MB Wind Vectors
A common denominator of the composite of past flood events is Gulf of Mexico, Atlantic and Pacific ocean moisture sources feeding heavy-excessive precipitation amounts.
This is a positive mountain torque pattern with inflow and orographics favoring locations along and west of the Eastern Continental Divide.
Composite Climatology For 9 Different Flood Events_Mean Sea Level Pressure
So, it really should not be surprising to see where the heaviest precipitation has fallen in this pattern given what past climatology illustrates.
NWS Precipitation Analysis and Doppler Estimated_Past 60-Days
It should also be no surprise, that real concern exists for the upcoming pattern if the first graphic in this section, and this 6-10 day graphic (below), verifies.
European 51-Member Ensemble Mean 500 MB Height Anomalies Forecast_Days 6-10
More severe storms and flooding will occur in such a pattern, so stay tuned for future updates by late this week into early next week.
